1. Field of the Invention
The present invention relates to a size measurement apparatus for measuring a size of the subject on an image, a computer-readable size measurement program storage medium, an image display unit for displaying an image, and a computer-readable image display program storage medium.
2. Description of the Related Art
Hitherto, in the field of the medical treatment, a medical image, which is obtained through taking a picture of the inside of the body of the subject with an X-ray image taking apparatus, an ultrasonic apparatus, and an endoscope apparatus, etc. is widely used for the diagnosis of the condition of the subject. The use of the medical image for the diagnosis makes it possible to understand the progress of the condition of the subject without giving the subject external damage, and also makes it possible to obtain easily information necessary for the decision of the treatment policy.
Moreover, in recent years, there are widely used CR (Computed Radiography) device that obtains a digital medical image by using the radiation, CT (Computerized Tomography) device that obtains a tomographic image of a testee or subject by using the radiation, and MRI (Magnetic Resonance Imaging) device that obtain a tomographic image of a testee or subject by using a strong magnetic field. And a digital medical image is generally used instead of a medical image that uses a past X-ray film etc. Digitalizing of the medical image makes it possible to collectively manage clinical records and the like so that the clinical records can be shared via the network in two or more hospitals etc. Thus, even if the diagnosis and treatment section and the hospital change, a medical image and the clinical record where the case history till then is shown can be applied.
Here, at the time of an actual diagnosis, there is performed a comparison interpretation of radiogram wherein two or more medical images, which are taken in picture at different time on the same subject, are arranged and displayed on a monitor (For instance, refer to Japanese Patent Application Laid Open Gazette TokuKai 2004-96417). The comparison interpretation of radiogram can easily confirm the change in the size of the focus and the like, and thus it is one of the methods very useful for the diagnosis of the effect of the condition and treatment. However, the method of the comparison interpretation of radiogram involves such a problem that even if two or more medical images are arranged and the area of interest that seems to be changes is expanding displayed, the change is blind when the increase and decrease of the focus is a little.
In this respect, non-patent reference 1 discloses a technology in which an image feature such as the luminance distribution in the tumor area in the image is analyzed, and the outline of the tumor is acquired by extracting the area that has the image feature approximated to an image feature of the tumor area from among a medical image. The change of the condition and the result of the treatment can more certainly be recognized by acquiring the outline of the tumor area in a medical image by using this technology, and measuring a length diameter and a short diameter of the tumor based on the outline.
Non-patent reference 1: K. Okada, D. Comaniciu, A. Krishnan, “Robust Anisotropic Gaussian Fitting for Volumetric Caracterization of Pulumonary Nodules in Multislice CT”, IEEE Trans. Medical Imaging, Vo. 24, No. 3, pp. 409-423, 2005
However, it might be very difficult to take a picture of the subject at mutually different time by the same posture as fit, and the position and the angle of the subject that is reflected in a medical image might shift by the change and breath, etc. of the physique. Moreover, there is frequent such a case that the shape such as tumors is near circle and asymmetry, and thus the direction of a length diameter and a short diameter changes greatly as a little change of the shape. Therefore, the shape such as tumors is unsuitable to the comparison. It is requested for the comparison interpretation of radiogram that the change of the condition and the effect of the treatment are understood accurately, and the development of the technology that can measure the size that is appropriate for the comparison is demanded.